Substrate processing apparatus and substrate processing method

ABSTRACT

A substrate processing apparatus for supplying a treatment liquid onto the surface of a substrate to treat the same. This apparatus is provided with: a spin chuck for holding and rotating a substrate; a nozzle for supplying a treatment liquid to the substrate held by the spin chuck; a circulating passage arranged such that the treatment liquid supplied to the substrate from the nozzle and used for substrate treatment is circulated to the nozzle and reutilized for substrate treatment; a metal contamination amount measuring device for measuring the metal contamination amount in the treatment liquid passing through the circulating passage; and a judgment processing unit for judging whether or not the value measured by the metal contamination amount measuring device has exceeded a predetermined set value.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to substrate processing apparatusfor and substrate processing method of supplying a treatment liquid ontothe surface of a substrate to treat the same, and more particularly tosubstrate processing apparatus and method to be applied to a process inwhich a treatment liquid is contaminated by metal. Examples of asubstrate to be treated, include a semiconductor wafer, aliquid-crystal-display-device glass substrate, a plasma-display glasssubstrate and the like.

[0003] 2. Description of Related Art

[0004] Higher-density integration and faster operation of semiconductorintegrated circuit elements are the requirements of the marketplace. Tomeet such requirements, copper wirings lower in resistance areincreasingly used instead of conventional aluminium wirings. When acopper wiring is combined with a low-permittivity insulating film (aso-called Low-k film or insulating film made of material of whichrelative permittivity is smaller than that of silicon oxide) to form amulti-layer wiring, this achieves an integrated circuit element operableat a very high speed.

[0005] Copper wirings at different layers are connected to each otherthrough a copper plug embedded in a via formed in the interlaminarinsulating film. To form a fine wiring pattern, a via having a highaspect ratio is required. To form such a via, there is applied a dryetching method represented by a reactive ion etching.

[0006] According to the dry etching, however, not only the film to betreated but also a resist are corroded. A part of the resist is thenchanged in quality and remains, as a polymer (resist residue), on thesubstrate surface. Because the wiring pattern is fine, the polymer mustsecurely be removed from the substrate before the subsequent step.

[0007] Polymer removal is carried out by supplying a polymer removingliquid onto the substrate to selectively etch the polymer.

[0008] The polymer contains copper scattered during the dry etchingstep. The copper is dissolved as copper ions in the polymer removingliquid. Accordingly, the polymer removing liquid after used forsubstrate treatment is thrown away at the present time.

[0009] However, the polymer removing liquid comprises an organic solventmixture having a complicated composition and is therefore expensive.Accordingly, to reduce the production cost of semiconductor devices andthe like, it is worth considering that the polymer removing liquid isnot thrown away after single-use, but the used polymer removing liquidis collected and reutilized.

[0010] However, while the polymer removing liquid is repeatedlycollected and reutilized, copper ions are accumulated in the polymerremoving liquid, causing the same to be a metal contamination source.More specifically, copper ions are attached to the reverse side of asubstrate or to other portions (oxide film surface and the like) of thesubstrate surface than the copper thin film. Such copper ionscontaminate other substrate processing apparatus to which the substratehas been transferred for other treatment. This results in contaminationof other substrates. As a result, there is a risk of having a profoundeffect on the characteristics of semiconductor devices or the like.

[0011] Similar problems may be expected not only in the polymer removingtreatment, but also in a treatment in which metal contamination isaccumulated in a treatment liquid, such as a bevel etching treatment forselectively removing a copper thin film at the peripheral edge of thesurface of a semiconductor wafer, a reverse-side etching treatment forremoving the metal contamination at the reverse side of a semiconductorwafer, or the like.

SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to provide substrateprocessing apparatus and substrate processing method which enable atreatment liquid to be reutilized, yet preventing metal contaminationfrom being excessively accumulated in the treatment liquid.

[0013] The present invention provides a substrate processing apparatusfor supplying a treatment liquid onto the surface of a substrate totreat the same. This apparatus comprises: a circulating passage arrangedsuch that a treatment liquid is supplied to a substrate and thetreatment liquid used for substrate treatment is circulated andreutilized for other substrate treatment; a metal contamination amountmeasuring device for measuring the metal contamination amount in thetreatment liquid passing through the circulating passage; and a judgmentprocessing unit for judging whether or not the value measured by themetal contamination amount measuring device has exceeded a predeterminedset value.

[0014] According to the arrangement above-mentioned, the treatmentliquid for treating the substrate surface, is circulated through thecirculating passage and is therefore repeatedly utilized. Provision ismade such that the metal contamination amount in the treatment liquidcirculating in the circulating passage is measured by the metalcontamination amount measuring device and that it is judged whether ornot the measurement value has exceeded the predetermined set value.

[0015] Accordingly, the judgment result obtained by the judgmentprocessing unit can be utilized for generating an alarm or forcontrolling the supply of a new treatment liquid. This enables thetreatment liquid to be repeatedly utilized within the range in which themetal contamination amount is not excessively increased. This reducesthe consumption of the treatment liquid, thus not only lowering thesubstrate processing cost, but also preventing the metalliccontamination from being excessively accumulated in the treatmentliquid. This not only prevents devices formed on the substrate frombeing deteriorated in characteristics, but also prevents other substrateprocessing apparatus from being contaminated.

[0016] The metal contamination amount measuring device may sample thetreatment liquid passing through the circulating passage, and maymeasure the metal contamination amount in the treatment liquid thussampled. In such a case, the sampled treatment liquid is preferably notreturned to the circulating passage, but is thrown away.

[0017] More specifically, the metal contamination amount measuringdevice may be arranged such that a chelating agent is mixed with asampled treatment liquid to form a complex of metallic ions in thetreatment liquid, that potential is applied to a mercury electrode sodisposed as to come in contact with the sampled treatment liquid,causing the metallic ions formed as the complex to be adsorbed by thesurface of the mercury electrode, and that the potential of the mercuryelectrode is then scanned. The complex is reduced and eluted from themercury electrode surface with the inherent potential according to thetype of the metallic ions. Accordingly, the metal type can be judgedbased on the potential value at that time, and the metallic ionconcentration is measured based on the current value at that time.

[0018] A filter having an intake port through which the treatment liquidcan be sampled, may be interposed in the circulating passage. In such acase, the metal contamination amount measuring device is preferablyarranged to sample the treatment liquid from this filter intake port.

[0019] According to the arrangement above-mentioned, the treatmentliquid can be sampled with the use of the filter intake port interposedin the course of the circulating passage. Accordingly, the metalcontamination amount can be measured without the circulating passagecomplicated in arrangement.

[0020] The intake port may be an air vent or drain port of the filter.

[0021] The filter may be a chemical filter for catching the metalliccontaminating material in the treatment liquid. According to thearrangement above-mentioned, the metallic contaminating material in thecirculating passage can be caught by the chemical filter, thus enablingthe treatment liquid to be lengthened in lifetime. This accordinglyreduces the consumption of the treatment liquid, thus lowering thesubstrate processing cost.

[0022] Provision may be made such that an alarm generating devicegenerates an alarm, in response to the judgment made by the judgmentprocessing unit that the value measured by the metal contaminationamount measuring device has exceeded the preset value. According to thisarrangement, it is informed to the operator that the metal contaminationamount in the treatment liquid circulating in the circulating passagehas exceeded the preset value. Thus, the operator becomes aware of thenew treatment liquid supply time or the treatment liquid replacementtime.

[0023] Provision may be made such that a new treatment liquid issupplied into the circulating passage, in response to the judgment madeby the judgment processing unit that the value measured by the metalcontamination amount measuring device has exceeded the preset value.According to this arrangement, when the metal contamination amount inthe treatment liquid has exceeded the preset value, a new treatmentliquid is automatically supplied into the circulating passage, thussecurely preventing a substrate from being treated with a treatmentliquid excessively contaminated with metal.

[0024] Prior to the supply of a new treatment liquid, a part or all ofthe treatment liquid passing through the circulating passage ispreferably discharged. According to this arrangement, apart or all ofthe treatment liquid can be replaced with a new treatment liquid.

[0025] The present invention provides a substrate processing method ofsupplying a treatment liquid to the surface of a substrate to treat thesame. This method comprises: a step of circulating a treatment liquid ina circulating passage arranged such that the treatment liquid issupplied to a substrate and the treatment liquid used for substratetreatment, is circulated and reutilized for other substrate treatment; ametal contamination amount measuring step of measuring the metalcontamination amount in the treatment liquid passing through thecirculating passage; and a step of judging whether or not the valuemeasured at the metal contamination amount measuring step has exceeded apredetermined set value.

[0026] The circulating passage may comprise a treatment liquid tankwhich stores a treatment liquid, a treatment liquid supply passagethrough which the treatment liquid is supplied from the treatment liquidtank to a substrate to be treated, and a treatment liquid collectingpassage through which the treatment liquid after used for substratetreatment is collected to the treatment liquid tank.

[0027] In such a case, the metal contamination amount measuring deviceis preferably arranged to measure the metal contamination amount in thetreatment liquid passing through the treatment liquid supply passage.However, there may be measured the metal contamination amount in thetreatment liquid stored in the treatment liquid tank or the metalcontamination amount in the treatment liquid passing through thetreatment liquid collecting passage.

[0028] A substrate treatment to which the substrate processing apparatusor the substrate processing method of the present invention is applied,is a process in which metallic ions mixingly enter the treatment liquidto be used in a circulating manner. Examples of such a process include aprocess of treating a substrate having a metallic film formed on thesubstrate surface, a process of treating a substrate having metallicions attached to the substrate surface, a process in which a treatmentliquid passes through a metallic pipe (SUS pipe), and the like.

[0029] The treatment liquid may be deionized water or a chemical fluid.The chemical fluid may comprise an acid such as a hydrofluoric acid, anitric acid, an acetic acid, a hydrochloric acid, a sulfuric acid or thelike, or may comprise alkali such as ammonia or the like. The chemicalfluid may be a mixture of any of the acids or alkali above-mentionedwith an oxidizing agent such as a hydrogen peroxide solution, ozone orthe like, or with an organic solvent such as methanol or the like.Further, the present invention may be applied to a process using apolymer removing liquid as the chemical fluid.

[0030] As the polymer removing liquid, there may be used at least oneselected from a liquid comprising an organic alkali liquid, a liquidcomprising an organic acid, a liquid comprising an inorganic acid, and aliquid comprising a material of the ammonium fluoride type. Examples ofthe liquid comprising an organic alkali liquid, include a liquidcomprising at least one selected from DMF (dimethyl formamide), DMSO(dimethyl sulfoxide), hydroxylamine, and choline. Examples of the liquidcomprising an organic acid include a liquid comprising at least oneselected from a citric acid, an oxalic acid, an iminodi acid and asuccinic acid. Examples of the liquid comprising an inorganic acidinclude a liquid comprising at least one selected from a hydrofluoricacid and a phosphoric acid. As the polymer removing liquid, there is aliquid comprising at least one selected from liquids each comprising anyof 1-methl-2pyrrolidone, tetrahydrothiophene 1.1-dioxide,isopropanolamine, mono-ethanolamine, 2-(2aminoethoxy) ethanol, catechol,N-methylpyrrolidone, aromatic diol, tetrachloroethylene, and phenol.More specifically, examples of such a liquid include a mixture liquid of1-methyl-2pyrrolidone with tetra-hydrothiophene 1.1-dioxide andisopropanolamine, a mixture liquid of dimethyl sulfoxide withmonoethanolamine, a mixture liquid of 2-(2aminoethoxy)ethanol withhydroxyamine and catechol, a mixture liquid of 2-(2aminoethoxy)ethanolwith N-methylpyrrolidone, a mixture liquid of monoethanolamine withwater and aromatic diol, and a mixture liquid of tetrachloroethylenewith phenol. Further, there may be stated a liquid comprising at leastone selected from amines such as triethanolamine,pentamethyldiethylenetriamine or the like, propylene glycol, dipropyleneglycol monomethyl ether or the like.

[0031] Examples of metal which mixingly enters the treatment liquid andof which contamination amount can be detected, include copper,aluminium, iron, zinc, chrome, nickel and the like.

[0032] These and other features, objects, advantages and effects of thepresent invention will be more fully apparent from the followingdetailed description set forth below when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a diagram illustrating the arrangement of a substrateprocessing apparatus according to an embodiment of the presentinvention;

[0034]FIG. 2 is a block diagram illustrating the functional arrangementof a controller of the substrate processing apparatus in FIG. 1; and

[0035]FIG. 3A and FIG. 3B are diagrams illustrating portions of otherembodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036]FIG. 1 is a diagram illustrating the arrangement of a substrateprocessing apparatus according to an embodiment of the presentinvention. This substrate processing apparatus is arranged to supply atreatment liquid from a treatment liquid supply nozzle 1 onto thesurface of a substrate W such as a semiconductor wafer, aliquid-crystal-display glass substrate or the like. Further, thisapparatus is of the single-substrate-processing type in which substratesW are processed one by one. More specifically, one substrate W isrotated as held by a spin chuck 3 disposed in a treatment cup 2, and atreatment liquid from the treatment liquid supply nozzle 1 is suppliedonto the surface of the substrate W under rotation.

[0037] The treatment liquid is stored in a treatment liquid tank 4.Provision is made such that the treatment liquid is pumped out by a pump5 and supplied to the treatment liquid supply nozzle 1 through atreatment liquid supply passage 10. Disposed along the treatment liquidsupply passage 10 are a thermocontroller 6 for controling thetemperature of the treatment liquid, a chemical filter 20 for catching ametallic contaminating material in the treatment liquid passing throughthe treatment liquid supply passage 10, and a three-way valve 7 servingas a switching mechanism for selectively guiding the treatment liquid tothe treatment liquid supply nozzle 1 or the treatment liquid tank 4.

[0038] On the other hand, to collect, to the treatment liquid tank 4,the treatment liquid after used for treating the substrate W, atreatment liquid collecting passage 12 is disposed between the treatmentcup 2 and the treatment liquid tank 4. There are further disposed adeionized water supply passage 13 and a chemical fluid supply passage 14for respectively supplying deionized water and a chemical fluid to thetreatment liquid tank 4, and these passages 13 and 14 are respectivelyconnected to a deionized water supply source and a chemical fluid supplysource through a deionized water supply valve 15 and a chemical fluidsupply valve 16, respectively.

[0039] Provision is made such that the treatment liquid in the treatmentliquid tank 4 is discharged, as necessary, to a drain line through adrain valve 17.

[0040] A controller 30 comprising a microcomputer and the like isdisposed for controlling the three-way valve 7, the deionized watersupply valve 15, the chemical fluid supply valve 16 and the drain valve17. The controller 30 controls the three-way valve 7 such that thetreatment liquid from the treatment liquid supply passage 10 is suppliedto the treatment liquid supply nozzle 1 when conducting a treatment onthe substrate W with the treatment liquid, and that the treatment liquidfrom the treatment liquid supply passage 10 is guided to the treatmentliquid tank 4 through a treatment liquid return passage 11 when notreatment is conducted on the substrate W. Further, the controller 30 isarranged such that, when replacing the treatment liquid in the treatmentliquid tank 4 with a new treatment liquid, the drain valve 17 is openedto discharge a part or all of the treatment liquid in the treatmentliquid tank 4, and that the deionized water supply valve 15 and/or thechemical fluid supply valve 16 are then opened to supply new treatmentliquids into the treatment liquid tank 4.

[0041] The chemical filter 20 has air vents 21 and 22 respectively atthe primary and secondary sides, and also has a drain port 23. Theprimary-side air vent 21 and the secondary-side air vent 22 areconnected to the treatment liquid tank 4 through air vent pipes 24, 25,respectively. On the other hand, the drain port 23 is connected to ametal contamination amount measuring device 40 through a sampling pipe26.

[0042] The metal contamination amount measuring device 40 incorporates apump and samples, for example at regular time intervals, a predeterminedamount of the treatment liquid passing through the treatment liquidsupply passage 10 via the drain port 23 of the chemical filter 20 andthe sampling pipe 26. The device 40 then measures the metalcontamination amount (metallic ion concentration) of the treatmentliquid thus sampled, and gives the measurement result to the controller30.

[0043] The controller 30 compares, with a predetermined set value, themetal contamination amount measured by the metal contamination amountmeasuring device 40, and controls, based on the comparison result, thedeionized water supply valve 15, the chemical fluid supply valve 16 andthe drain valve 17. As a result, the treatment liquid in the treatmentliquid tank 4 is replaced with new treatment liquids at a suitable time.

[0044] When the metal contamination amount measured by the metalcontamination amount measuring device 40 has exceeded the preset valueabove-mentioned, the controller 30 actuates an alarm device 50 toinform, to the operator of this substrate processing apparatus, the factthat the time of replacement of the treatment liquid has come. The alarmdevice 50 may be arranged to generate an alarm sound such as a buzzer orthe like, or to generate an alarm light such as a signal display lamp,or to display an alarm message on a display screen.

[0045] For example, the metal contamination amount measuring device 40may be arranged such that a chelating agent is mixed with a sampledtreatment liquid to form a complex of metallic ions in the treatmentliquid, that potential is applied to a mercury electrode disposed in thetreatment liquid, causing the metallic ions formed as the complex to beadsorbed by the surface of the mercury electrode, and that the potentialof the mercury electrode is then scanned. By scanning the potential, thecomplex is reduced and eluted from the mercury electrode surface withthe inherent potential according to the metal type. The metal type canbe judged based on the potential at that time, and the metallic ionconcentration is measured based on the current value at that time.

[0046] Because mercury or a chelating agent mixingly enters thetreatment liquid sampled for measurement of metal contamination amount,the treatment liquid thus sampled is not returned to the treatmentliquid tank 4 or the like, but is wasted.

[0047]FIG. 2 is a block diagram illustrating the functional arrangementof the controller 30. The controller 30 substantially has the followingfunctional processing units to be realized by executing a predeterminedprogram by the microcomputer. More specifically, the controller 30 has apassage changeover control unit 31 for controlling the three-way valve 7such that the treatment liquid from the treatment liquid supply passage10 is supplied to the treatment liquid supply nozzle 1 when executing atreatment on a substrate W with the treatment liquid, and that thetreatment liquid from the treatment liquid supply passage 10 is guidedto the treatment liquid tank 4 through the treatment liquid returnpassage 11 when no treatment is executed on a substrate W. Further, thecontroller 30 has: a judgment processing unit 32 for judging whether ornot the metal contamination amount measured by the metal contaminationamount measuring device 40 has exceeded the preset valueabove-mentioned; an alarm generation control unit 33 for actuating thealarm device 50, in response to the judgment made by the judgmentprocessing unit 32 that the metal contamination amount has exceeded thepreset value; a drainage control unit 34 for opening the drain valve 17for discharging a part or all of the circulating treatment liquid, inresponse to the judgment made by the judgment processing unit 32 thatthe metal contamination amount has exceeded the preset value; and a newliquid supply control unit 35 arranged such that when the judgmentprocessing unit 32 judged that the metal contamination amount hadexceeded the preset value, the deionized water supply valve 15 and thechemical fluid supply valve 16 are opened to supply new treatmentliquids to the treatment liquid tank 4 after a part or all of thetreatment liquid has been discharged by controlling the opening/closingof the drain valve 17 by the drainage control unit 34.

[0048] Provision may be made such that the treatment liquid in thetreatment liquid tank 4 is not discharged prior to the supply of newliquids. In such a case, provision may be made such that, in response tothe judgment made by the judgment processing unit 32 that the metalcontamination amount has exceeded the preset value, the new liquidsupply control unit 35 opens the deionized water supply valve 15 and thechemical fluid supply valve 16 without waiting for drainage.

[0049] Further, there maybe present a period of time during which thereare simultaneously carried out both the drainage of the treatment liquidin the treatment liquid tank 4 and the supply of new liquids from thedeionized water supply valve 15 and the chemical fluid supply valve 16.

[0050] In the substrate processing apparatus having the arrangementabove-mentioned, the treatment liquid in the treatment liquid tank 4 issupplied to a substrate W from the treatment liquid supply nozzle 1through the treatment liquid supply passage 10, and the treatment liquidafter used for treatment of the substrate W is collected to thetreatment liquid tank 4 through the treatment liquid collecting passage12. More specifically, the treatment liquid tank 4, the treatment liquidsupply passage 10 and the treatment liquid collecting passage 12 form acirculating passage for circulating the treatment liquid forreutilization. This enables the treatment liquid to be repeatedly used,thus reducing the consumption of the treatment liquid, resulting inreduction of the cost required for substrate treatment.

[0051] On the other hand, the substrate processing apparatus accordingto this embodiment is arranged such that the metal contamination amountin the treatment liquid passing through the treatment liquid supplypassage 10, is measured by the metal contamination amount measuringdevice 40, and that when the measurement result has exceeded apredetermined set value, the treatment liquid in the treatment liquidtank 4 is then replaced with a new treatment liquid. This does notinvolve the likelihood that the treatment liquid to be supplied onto thesurface of a substrate W contains a large amount of metalliccontaminating material, thus preventing the substrate W from beingundesirably contaminated by metal. Thus, no bad influence is exerted tothe characteristics of devices formed on the substrate W, and neitherother substrate processing apparatus nor other substrates arecontaminated by metal.

[0052] Further, when the metal contamination amount has exceeded thepreset value, the alarm device 50 generates an alarm. Thus, the operatorcan become aware of the fact that the metal contamination amount in thetreatment liquid has reached the preset value and the fact that thetreatment liquid is accordingly replaced.

[0053] The substrate processing apparatus according to this embodimentcan be used, for example, as a polymer removing apparatus. Morespecifically, the present invention may be embodied in the form of asubstrate processing apparatus using, as the treatment liquid, a polymerremoving liquid for removing the resist residue (polymer) remaining onthe surface of a substrate W at the time when a copper thin film formedon the surface of the substrate W is patterned by dry etching. In such acase, the treatment liquid tank 4 stores a polymer removing liquid andthe spin chuck 3 holds a substrate W after a patterning treatment of acopper thin film has been executed by dry etching (substrate having acopper thin film on the surface).

[0054] The polymer mixingly contains a corroded resist and copper as thefilm material to be treated. When the polymer is removed from thesurface of the substrate W by the polymer removing liquid, the treatmentliquid or polymer removing liquid after supplied to the substrate W,mixingly contains copper ions. While the polymer removing liquid iscirculated and reutilized, copper ions are increasingly accumulated inthe polymer removing liquid.

[0055] In such a process, the metal contamination amount measuringdevice 40 samples, at regular time intervals, a predetermined amount ofthe polymer removing liquid from the treatment liquid supply passage 10,measures the metal contamination amount (copper ion concentration), andgives the measurement result to the controller 30. Accordingly, when thecopper ion concentration of the polymer removing liquid has reached apredetermined set value, the controller 30 opens the drain valve 17 todischarge a part or all of the polymer removing liquid in the treatmentliquid tank 4 and opens the deionized water supply valve 15 and/or thechemical fluid supply valve 16 to supply a new polymer removing liquidhaving a predetermined concentration to the treatment liquid tank 4.Thus, the circulation and reutilization of the polymer removing liquidrestrains the consumption thereof, while the polymer removing liquid canbe restrained from being excessively increased in copper ionconcentration.

[0056] Further, when there is used, as the treatment liquid, a chemicalfluid comprising an acid such as a hydrofluoric acid, a nitric acid, anacetic acid, a hydrochloric acid, a sulfuric acid or the like, thesubstrate processing apparatus above-mentioned may be used as an etchingapparatus (for example, bevel etching apparatus or reverse-side etchingapparatus) for etching a thin film formed on the surface of a substrateW, or as a substrate cleaning apparatus for cleaning the surface of asubstrate W under the etching action of the chemical fluid. It is amatter of course that the substrate processing apparatus above-mentionedmaybe applied to etching apparatus or substrate cleaning apparatus usinga chemical fluid comprising alkali such as ammonia or the like. Thechemical fluid to be used for the etching processing or substratecleaning processing may be a mixture liquid of any of the acids oralkali above-mentioned with an oxidizing agent such as a hydrogenperoxide solution, ozone or the like, or with an organic solvent such asmethanol or the like.

[0057] Examples of the metal which can be measured by the metalcontamination amount measuring device 40 include copper, aluminium,iron, zinc, chrome, nickel and the like. Accordingly, the substrateprocessing apparatus can widely be applied to a process having thepossibility of any of the metals above-mentioned mixingly entering thetreatment liquid.

[0058] The foregoing has discussed an embodiment of the presentinvention, but the present invention may also be embodied in othermanner. For example, the embodiment above-mentioned is arranged toautomatically replace the treatment liquid circulating in thecirculating passage by controlling the deionized water supply valve 15,the chemical fluid supply valve 16 and the drain valve 17. However,provision may be made such that when the controller 30 actuates thealarm device 50, the operator manually replaces the treatment liquid.Further, in the substrate processing apparatus above-mentioned arrangedto automatically replace the treatment liquid, the alarm device 50 maybe omitted.

[0059] When a part of the treatment liquid in the treatment liquid tank4 is discharged and new treatment liquids are supplied, the treatment ofthe substrate W can continuously be executed. However, when alltreatment liquid in the treatment liquid tank 4 is discharged at thetime of replacement of the treatment liquid, it is required to once stopthe substrate W treatment. To replace all the treatment liquid yetassuring the continuous substrate W treatment, for example two treatmentliquid tanks 4 may be disposed and used alternately.

[0060] In the embodiment above-mentioned, the metal contamination amountmeasuring device 40 is arranged to sample the treatment liquid from thedrain port 23 of the chemical filter 20. However, the treatment liquidmay be sampled from the primary-side air vent 21 as shown in FIG. 3A, orfrom the secondary-side air vent 22 as shown in FIG. 3B. Further, whenother filter is disposed at the treatment liquid supply passage 10 orthe like, the treatment liquid may be sampled from such a filter.Further, the treatment liquid may be sampled from the treatment liquidsupply passage 10 at a position different from the filter.

[0061] Further, the treatment liquid may be sampled from the treatmentliquid collecting passage 12, or the treatment liquid stored in thetreatment liquid tank 4 may be sampled for measurement of the metalcontamination amount.

[0062] Embodiments of the present invention have been discussed indetail, but these embodiments are mere specific examples for clarifyingthe technical contents of the present invention. Therefore, the presentinvention should not be construed as limited to these specific examples.The spirit and scope of the present invention are limited only by theappended claims.

[0063] This Application corresponds to Japanese Patent ApplicationSerial No. 2002-9131 filed on Jan. 17, 2002 with Japanese Patent Office,the disclosure of which is incorporated herein by reference.

What we claim is:
 1. A substrate processing apparatus for supplying atreatment liquid onto a surface of a substrate to treat the same,comprising: a spin chuck for holding and rotating a substrate; a nozzlefor supplying a treatment liquid to the substrate held by the spinchuck; a circulating passage arranged such that the treatment liquidsupplied to the substrate from the nozzle and used for substratetreatment is circulated to the nozzle and reutilized for substratetreatment; a metal contamination amount measuring device for measuring ametal contamination amount in the treatment liquid which circulates inthe circulating passage; and a judgment processing unit for judgingwhether or not a value measured by the metal contamination amountmeasuring device has exceeded a predetermined set value.
 2. A substrateprocessing apparatus according to claim 1, wherein the metalcontamination amount measuring-device samples the treatment liquidpassing through the circulating passage and measures the metalcontamination amount in the treatment liquid thus sampled.
 3. Asubstrate processing apparatus according to claim 2, wherein there isfurther disposed, in the circulating passage, a filter having an intakeport through which the treatment liquid is to be sampled, and the metalcontamination amount measuring device is arranged to sample thetreatment liquid from the intake port of the filter.
 4. A substrateprocessing apparatus according to claim 3, wherein the intake port is anair vent or drain port of the filter.
 5. A substrate processingapparatus according to claim 3, wherein the filter is a chemical filterfor catching the metallic contaminating material in the treatmentliquid.
 6. A substrate processing apparatus according to claim 1,further comprising: an alarm device for generating a predeterminedalarm; and an alarm generation control unit for actuating the alarmdevice to generate an alarm, in response to the judgment made by thejudgment processing unit that the value measured by the metalcontamination amount measuring device has exceeded the preset value. 7.A substrate processing apparatus according to claim 1, furthercomprising: a new liquid supply valve for supplying a new treatmentliquid to the circulating passage; and a new liquid supply control unitfor opening the new liquid supply valve to supply a new treatment liquidto the circulating passage, in response to the judgment made by thejudgment processing unit that the value measured by the metalcontamination amount measuring device has exceeded the preset value. 8.A substrate processing apparatus according to claim 7, furthercomprising: a drain valve for discharging a part or all of the treatmentliquid which circulates in the circulating passage; and a drainagecontrol unit for opening the drain valve to discharge a part or all ofthe treatment liquid circulating in the circulating passage, prior tothe supply of a new treatment liquid into the circulating passage fromthe new liquid supply valve controlled by the new liquid supply controlunit.
 9. A substrate processing apparatus according to claim 1, whereinthe treatment liquid is capable of removing a polymer, and the substrateprocessing apparatus is a polymer removing apparatus for removing apolymer remaining on the surface of a substrate.
 10. A substrateprocessing apparatus according to claim 1, wherein the treatment liquidis a chemical fluid containing an acid or alkali, and the substrateprocessing apparatus is an etching apparatus for etching a thin filmformed on the substrate surface.
 11. A substrate processing apparatusaccording to claim 1, wherein the treatment liquid is a chemical fluidcontaining an acid or alkali, and the substrate processing apparatus isa substrate cleaning apparatus for cleaning the substrate surface underthe etching action of the chemical fluid.
 12. A substrate processingmethod of supplying a treatment liquid to a surface of a substrate totreat the same, the method comprising: a substrate holding and rotatingstep of holding a substrate by a spin chuck and rotating the substrate;a treatment liquid supply step of supplying a treatment liquid from anozzle to the substrate held by the spin chuck during the substrateholding and rotating step; a step of circulating the treatment liquid ina circulating passage arranged such that the treatment liquid suppliedto the substrate from the nozzle and used for substrate treatment, iscirculated to the nozzle and reutilized for substrate treatment; a metalcontamination amount measuring step of measuring the metal contaminationamount in the treatment liquid passing through the circulating passage;and a step of judging whether or not a value measured at the metalcontamination amount measuring step has exceeded a preset value.
 13. Asubstrate processing method according to claim 12, further comprising analarm generating step of generating an alarm from an alarm device, inresponse to the judgment made at the judgment step that the valuemeasured at the metal contamination amount measuring step has exceededthe preset value.
 14. A substrate processing method according to claim12, further comprising a new liquid supply step of supplying a newtreatment liquid in the circulating passage, in response to the judgmentmade at the judgment step that the value measured at the metalcontamination amount measuring step has exceeded the preset value.
 15. Asubstrate processing method according to claim 14, further comprising adrain step of discharging a part or all of the treatment liquid passingthrough the circulating passage, prior to the new liquid supply step.16. A substrate processing method according to claim 12, wherein thetreatment liquid is a polymer removing liquid capable of removing thetreatment liquid which remains on the substrate surface.
 17. A substrateprocessing method according to claim 12, wherein the treatment liquid isa chemical fluid containing an acid or alkali to be used for etching athin film formed on the substrate surface.
 18. A substrate processingmethod according to claim 12, wherein the treatment liquid is a chemicalfluid containing an acid or alkali to be used for cleaning the substratesurface under an etching action.